Means for starting free piston engines



2 Sheets-Sheet 1 V H. AmcKE Filed may 17, 1934 MEANS FOR STARTING FREE PISTON ENGINES lnw entar:

Nov. 19, j{l940. H. JANlcKE 2,222,250

MEANS FOR STARTING FREE PISTON ENGINES Filed May 17, 1934 2 Sheets-Sheet 2 llcnnann ,laniche, hessau, Germany, assignor to Hugo Junkers, hayrisch-dell, llherbayein, her many, Therese wlluualoers, nee Tlennhold, Elantlng, Germany, administratriu or said lhlugo l'ers, deceased application ll/lay lll, rear, Serial l lo. 'l2d,lldl' lln Germany May 23, M33

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being made to act on the freely movable masses.

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lln tree piston engines comprising a gas compressor forming the energy consinning unit, it has been suggested to till the compressor spaces with com pressed gas, while the freely moving masses are loclrecl in their position by suitable means, and to thereafter release the locking means, thus a1lowing the treely moving masses to he accelerated by the expanding gas and to compress the gas in the motor cylinders.

When proceeding according to these prior sug-- gestions, only. a single impulse can he imparted to the freely moving mass and it is therefore necessary to create already during the first two strolres occiu'ring in opposite directions in the motor as well as in the energy consumer the conditions of operation corresponding to normal operation, which include sumcient compression or the motor charge and production of a final pressure in the compressor sufiicient for ordinary operation, in order to provide for a faultless oper atio-n oi the machine. in a reliable manner is connected with great ditti culties, more especially in the case oi multistage compressors.

according to the present invention this drawbaclr is obviated by providing a separate energy storer connected with the freely moving masses and charged with theenergy required for the starting of the engine, which is effected in the following manner: The energy stored in the energy storm is transmitted to the freely moving mass which now executes its first stroke, whereby the motor charge is compressed. The compressed charge in the motor cylinder is now ignited and the gases of combustion force the freely moving mass back, whereby theenergy storer is partly reloaded. This new quantity of energy available is now transmitted to the freely moving mass during the next following starting stroke. On the charge in the motor cylinder being now ignited, the freely moving mass is'once more imparted an impulse and the energy storer is again reloadedup to part of its first charge, and so forth. Thus during several starting strokes, the energy storer delivers to the freely moving mass gradually decreasing quantities of energy, while this'mass, during the intermediate strokes. delivers gradually decreasing quantities of energy To create these conditions lift, 23d--5li) to the storer, until finally these latter quantities of energy have become equal to zero, so that the storer runs idle. At the same time the energy consumer, for instance a compressor, is controlled in such manner, that when beginning the starting, it will talre up little or no energy, the energy talren up increasing however from one working strolre to the other in the same proportion as the delivery of energy from the energy storer decreases, so that when this latter begins to run idle, the part of the engine, which consumes energy, has reached its full output. The gradual loading of the energy consumer may be efiected automati cally in dependency from the unloading of the starting energy storer or the gradual unloading oi the starting storer may be effected automatically in dependency from the increasing loading oi the energy consumer. Preferably the starting energy storer is so designed that it can be disengaged from the freely moving mass after normal condi- M tions of operation have been reached.

Preferably when charging such storers before the starting, the freely moving masses are loclred in their position in a well known manner, by suit able locking devices, which are released, when the starting stroke begins.

Lli gas under pressure is used for starting, the gas may be caused to how into the storing cylinder from 'a reservoir during the starting strolre. I may however also supply starting energy to the storer under the formoi chemically bound energy, for instance in an explosive, and in that case no locking means are required for locking the freely moving masses. If compressors are used, throttling means, which are gradually opened during the starting process, may be inserted in the supply pipe and in the case of multistage compressors also between the individual stages.

The amount of starting energy required and consequently also the size of the starting storer may be reduced by reducing the resistance to be overcome during the starting stroke, for instance by diminishing the quantity of gas to be compressed in the motor cylinder, part of the charge in the motor cylinder being re-exhausted for this purpose. Preferably this re-exhausting is rendered dependent from the gradual translation of lllll the how or energy from the starting storer to the ied during the start, to be thereafter gradually increased in the course of energy translation.

In the drawings amxcd to this specification and 55- forming part thereof some embodiments of an engine provided with a starting device according to my invention are illustrated diagrammatically by way of example.

In the drawings- Figs. 1 and 2 are axial sections 01 two embodiments of a free piston engine according to my invention, a pneumatic energy storing device.

In Figs. 1 and 2, corresponding parts are marked with the same reference numerals.

Referring first to Fig. 1, the free piston engine contains two reciprocating bodies, each comprising a motor piston i, a compressor piston 2 and a storing piston 3, reciprocating in opposite directions in a motor cylinder i i, compressor cylinders I2 and storing cylinders l3, respectively. 4 and 5 are inlet ports and exhaust ports provided in the wall of the motor cylinder ii. The compressor cylinders i2 are provided with suction valves 7 and pressure valves 8. In order to secure exact opposite reciprocation, the reciprocating bodies are coupled with each other by means of a coupling device comprising toothed racks id, 14', connected to the compressor pistons 2, respectively, and a pinion i5 engaging the toothed racks and rotatably secured to the casing (not shown) of the engine. it is an inlet nozzle for delivering fuel into the cylinder 9 i. The reciprocating bodies can be arrested by means of a locking device comprising a latch l8 releasable by means of a spring-loaded hand lever is and cooperating with a locking tooth l'i provided on the rack M. In the position of the locking device shown in Fig. l the reciprocating bodies are locked approximately in their outer dead centre positions.

Each storing chamber 9 is connected to a supply of compressed air (not shown) by means of a pipe 2i, 2. starting valve 22 and an inlet pipe 23. In the engine shown in Fig. l a starting storer is provided on each side of the engine. If desired, however, a storing device may be provided only on one side, influencing the other side of the engine by means of the coupling gear i l, i4, 85.

In order to obtain a suitable operating diagram of the storing device and to reduce its dimensions, means are provided for allowing compressed air to flow into the storing cylinders during a portion of the starting stroke. "In order to maintain the delivery of compressed air to the storing cylinders and to stop it a predetermined time after the beginning of the starting stroke, an outlet 25 is provided in the wall of each storing chamber Q in such manner, that the storing pistons 3 move past the outlets 25 only after having carried out a considerable portion of their starting stroke. The outlets 25 constitute connections between each storing chamber 9 and auxiliary cylinders 26', in which auxiliary pistons 26 are arranged for recip= rocation, the piston rods 21 of which extend into the pipes 23 and which comprise bores 28, through which compressed air flows to the storing chambers 9, until the pistons 26 are forced apart by the air escaping from the storing cylinders 9 through the openings 25. 21 are buttons for re-setting the pistons 26 into their initial positions after the stopping of the engine.

In order to unload the energy consumer, com= prising compressor pistons 2 and compressor chambers 6 forming part of cylinders l2, during valve is loaded by a spring 33 arranged in the valve casing 34, so as to abut against the end wall thereof, and a piston 35 is arranged in the casing 34 and connected to the valve disc 32 in such manner that a discharge of compressed gas or air from the chambers 6 takes place only, when a predetermined pressure adapted for the operation of the engine is reached. To this end the casing '34 is connected onthe side of the piston 35 opposite to the spring 33 by means of a connection 36 to a container 20 communicating with one of the storing chambers 9 through a small bore 31. 38 are exhaust pipes connected to the storing chambars 9, respectively, and provided with control valves 39.

The exhaust pipe 46 of the motor cylinder is connected to a suitably arranged exhaust port ti by means of a connection 45. 40 is avalve disc loaded by a spring 42 arranged in a cylinder 46 and normally closing valve 40. The upper end of the valve stem is provided with a piston 5% arranged in the cylinder it and lifted by the spring Q2. The upper part of the cylinder i t is connected to the container 2i! by means of a connection 63.

The operation of the engine is as follows:

Before the start all parts of the engine are in the positions shown in Fig. l, the pistons 26 being set by means of the buttons 21' and the reciproeating bodies being brought into their outer dead 5 centre positions by suitably rotating the pinion i5 by means of a. crank handle (not shown) or the like. In this position the parts are secured by means of the locking device i7, H8. The exhaust valves 39 and the valves 32 and 40 are closed. When the inlet valves 22 are opened, compressed gas will flow into the storing chambers 8 and the container 22. In consequence thereof valves 32 and 26 will be opened, since the compressed air is fed to the cylinders 34 and 54'. Now the locking device ii, iii is released by depressing the lever W, so that the flying bodies are moved inwardly by the compressed air present in the storing chambers 9 and the air entering these chambers throughthe pipes 2|, 23. During the inward stroke air is sucked into the chambers 6 through suction valves 5. During the last part of the stroke the pistons 3 move past the openings 25, so

that compressed air enters the cylinders 26' and moves the pistons 26, whereby the piston rods 21 close the connections 23 and the flow of compressed air into the storing chambers 9 is interrupted. A portion of charging air will be discharged during the stroke from the motor cylinder ii through the exhaust port 40, connection 45 and exhaust pipe 46. The charge in the motor cylinder ii, after having been compressed, is ignited whereby the flying bodies are driven outwards, compressing the air in the compressor cylinders i3, whereafter the cycle is repeated. During the first starting strokes the pressure in the container 28 is not materially affected Owing to the small diameter of the bore 31. In consequence thereof valve 32 remains open and the compressors 2, 6 run idle during the starting strokes.

In order to gradually transfer the load from the starting device onto the compressors, the

,valves 39 are slowly opened. In consequence thereof the pressures in the storing chambers l and the container 20 are diminished, so that the valves 32 and 40 are gradually closed. By the closing of valve 32 the compressors are gradually loaded in correspondence to the unloading of the storing devices .by the discharge of air encased ing air can escape from the motor cylinder ll,

so that the engine now operates in the same manner as an ordinary free piston engine.

Referring now to Fig. 2, a container to is provided connecting the connection lid to the discharge pipe ti. The container is dimensioned in such manner as to be charged to normal operating pressure Within a predetermined number of strokes after the starting of the engine. llhus;

valve ti will open after the normal pressure has been reached in the container lit. The inlet pipes it are directly connected to the storing chambers ll, displaceable bores corresponding to bores 2d of the device shown in Fig. 1, being arranged in the outlet pipes tilt oi the storing chambers d, the outlet valves lit shown in Figgfil' being omitted in Fig. 2. The bores lid are provided in piston rods ll connected to auxiliary pistons ld arranged in cylinders till which are connected to the container til by means of connections it respectively. The pistons till are loaded by means oi springs ht abutting against discs tile and arranged in casings lite. lhe discs title are connected to the piston rods ll, While discs are adjustable by means of ad lusting screvvs eutending through the outer end Walls of the casings filo. Obviously the pistons ll] will he moved against the action of the springs when the pressure in the container til increases. When no pressure exists in container the pistons ill are in a position in which the pipes are closed by the piston rods til. The pipes are gradually opened, when the pressure in container at increases gradually.

Besides this a device is provided for automatically changing the fuel delivery to the motor cylinder l l during the starting. To this end the piston t l of the incl delivery pump, the cylinder lid of Whichis connected in the usual manner to the fuel delivering nozzle ill oi the cylinder l l, is driven from a rotating cam lit by means of a douhle-armed lever pivoted to the outer end of the piston at and sliding with one end on the cant The other end oi the lever is connected to the rod lit oi a piston till arranged in a cylinder tilt" coiniected to the connection dill. ill is a spring forcing the piston to the left.

When the pressure in the container increases,

the lever is rotated in such manner that the piston ti l passes over an increasing portion oi the inlet openingsl or the cylinder ti l, so that the amount of fuel delivered to the motor cylinder it increases with the increase. of pressure in the container ltd.

The operation oi this device is substantially the same as that or the device shown in Fig. 1, except that the opening cl valve it is controlled by the increasing pressure in the container ht and that this pressure at the same time controls the opening of the pipes it, so that the storage de vices are gradually unloaded, While the compressors are loaded by the opening of the valve Further in correspondence to the increase of pressure in the container 50 the output of the fuel delivery pump is increased.

ll Wish it to be understood-that I do not desire to be limited to the exact details of construction shown and described, for obvious modifications will occur to a person skilled in the art.

I claim:

1. A free piston engine comprising in combination, a free piston including a motor piston arranged for operation in a motor cylinder, a compressor piston arranged for operation in a compressor cylinder, and an auxiliary piston arranged for operation in an auxiliary cylinder; a space in said auxiliary cylinder located on the side of the face of said auxiliary piston, means for connecting the auxiliary cylinder space with a source of gas under pressure and for shutting off said space from this source after it has been filled with gas under pressure; an outlet leading'into the open provided on the auxiliary cyl inder, a valve for shutting off and gradually open 'ing said outlet; a pressure pipe associated with said compressor cylinder, a valve provided in said pressure pipe and adapted to adord passage to the pressure gas coming from the compressor once a predetermined compression end-pressure has been reached, means controlled in dependency upon the variable gas pressure in a space, which is connected with one of the two last named cylinders, these means being adapted to influence the valve of the other of the said cylinders in a manner such that the compressor reaches the pressure corresponding to normal operation when the auxiliary cylinder is completely emptied of pressure gas and is connected with the at mosphere.

2. it. free piston engine comprising in combination, a freepiston including a motor piston arranged lor operation in a motor cylinder, a compressor piston arranged for operation in a coinpressor cylinder, and an auxiliary piston arranged for operation in an auxiliary cylinder; a space in said auxiliary cylinder located on the side of the face of said auxiliary piston, means for connecting the auxiliary cylinder space with a source of gas under presure and for shutting ofi said space from this source after it has been filled with gas under pressure; an outlet leading into the open provided on the auxiliary cylinder, a valve for shutting 0d and gradually opening said outlet; at pressure pipe associated with said compressor cylinder, a valve provided in said pressure pipe and adapted to afford passage to the pressure gas coming from the compressor once a predetermined compression end pressure has been reached, means controlled in dependency upon the variable gas pressure in a space, which. is connected with one of the two last named cyl inders, these means being adapted to influence the valve of the other oi the said cylinders in a manner such that the compressor reaches the pressure corresponding to normal operation when the auxiliary cylinder is completely emptied oi pressure gas and is connected with the at mosphere; means for temporarily locking the tree piston in substantially its outermost dead-center position with respect to the motor piston, and means for rendering said locking means inoperative.

, 3. A free piston engine according to claim 1, including a device for supplying fuel to the motor cylinder; a space connected with one of the other two cylinders and further connected with a pressure controlled device for varying the fuel supply in a manner such that the fuel supply, which is still low when the engine is started, increases to the amount corresponding to normal operation in proportion to the variation of the pressure prevailing in this space from the start to the attainment of normal operating conditions.

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l. A free piston engine according to claim 1,1n-

eluding. an exhaust port on the motor cylinder adapted ta be covered by the motor piston only after this piston has travelled a certain distance from its outermost dead center position, an adjustable closure member in said exhaust port; a space connected with one of the two other cyl inders and further connected with a pressure controlled device for varying the position of the closure member in a manner such that .this closure member, which is open when the engine is started, gradually throttles the exhaust port until it is completely shut in proportion to the variation of the pressure in the space from the start to the attainment of normal operating conditions.

5. A free piston engine comprising in combination, a free piston including a motor piston arranged for operation in a motor cylinder, a compressor piston arranged for operation in a compressor cylinder and an auxiliary piston arranged for operation in an auxiliary cylinder; a space in said auxiliary cylinder located on the side of the face of said auxiliary piston, means for connecting the auxiliary cylinder space with a source of gas under pressure and for shutting off said Y space from this source after it has been filled with gas under pressure; an outlet leading into the open provided on the auxiliary cylinder; a valve adapted for manually shutting off and gradually opening said outlet; a pressure pipe associated with said compressor cylinder, a reservoir constantly connected, through a narrow passage, with the auxiliary cylinder space and further connected with a spring loaded valve provided in said pressure pipe in a manner such that the pressure prevailing in said reservoir opposes the action of the spring of said spring-loaded valve; a shut-oil device provided in the gas supply pipe leading to the auxiliary cylinder, space, a piston connected with this device, a cylinder space surrounding'this piston and connected, through a channel, with the auxiliary cylinder space, said channel opening into the auxiliary cylinder space at a point which is laid open by the auxiliary piston when it has travelled, starting at its outermost dead center position, with respect to the motor piston, over a greater portion of its stroke.

6. A free piston engine comprising in combination, a free piston including a motor piston arranged for operation in a motor cylinder, a compressor piston arranged for operation in a compressor cylinder, and an auxiliary piston arranged for operation in an auxiliary cylinder; a space in said auxiliary cylinder located on the side of the face of said auxiliary piston, means for connecting the auxiliary cylinder space with a source of gas under pressure and for shutting off said space from its source after it has been filled with gas under pressure; an outlet leading into the open provided on the auxiliary cylinder, a shut-oil valve permanently loaded for closing provided in this outlet, a pressure pipe associated with said compressor cylinder, a container in said pressure pipe, a valve loaded for closing provided in the outlet from said container adapted to afford passage only when the pressure in said container has reached the amount of the normal compressor end pressure, said container being connected with a pressure controlled device for adjusting the shut-off valve in the outlet from the auxiliary cylinder in opposition to the spring arranged on said shut-on valve, in a manner such that this auxiliary cylinder outlet is completely open when the pressure in said container has reached the normal compressor end pressure.

v HERMANN JANICKE. 

